Questions tagged [rf]

Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.

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19 views

Compensation for dielectric losses in a coil?

Recently I built a helical resonator. It took me a good while to adjust it since I had to trim my coils much shorter than calculated. The calculation said 7.2 turns but it ended up being more like 6.5 ...
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71 views

Avoiding ground loops with multiple coax cables

I have to connect two devices with multiple coax cables each carring a signal that has frequency components ranging from DC to a few GHz. I don't know how to avoid ground loops with this type of ...
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56 views

How much RF power can a microstrip line handle?

Transmission lines on printed circuit boards must be impedance controlled lines since we want to transmit the full power and avoid the reflections. Microstrip lines have three parameters that we can ...
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81 views

Why is a horizontal rod a full wavelength oriented radially to a broadcast antenna not the best receiving antenna

I have always struggled to get a good physical understanding of Electromagnetic waves. I've done the whole Maxwell's equation approach, wrote boundary element solver tool but cannot rationalize that ...
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53 views

What is the purpose of these components in an LC Balun?

I'm trying to understand an antenna impedance matching / balun network that I came across in the receiving signal path in the schematics for the STEVAL-FKI868V2 S2-LP Evaluation Board, shown in the ...
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14 views

Butler Matrix simulation in Sonnet software

I am trying to replicate a 4 X 4 butler matrix using Sonnet Here is the sonnet design file : butler_matrix.son With conformal meshing (metal fill type) and course meshing, it still requires 14 GB of ...
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37 views

GPS module accuracy query

I have a GPS module with an accuracy of 1.5m + 1 ppm. Query: What is meant by 1 ppm accuracy, what does it symbolize?
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52 views

How do I create a 50ohm input impedance into this RF power measurement IC

I'm trying to create a basic RF power meter using the LTC5532. I want to add a SMA connector, and termination, so that the device has a 50ohm input impedance. I'll be using it primarily at 2.4Ghz, ...
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27 views

Relation between Centre Frequency and PLL locking range in FM Demodulation?

I am implementing an all digital PLL FM demodulating system using an FPGA. My center frequency is that of 125kHz and for some reason, the PLL is only locking at +/-38khZ from the center frequency, ...
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55 views

How the diode in this circuit achieves AM modulation

For the last week, I've been looking for a simple circuit to transmit VHF analogue TV video signals, so that I can transmit my Raspberry Pi output to a TV set. Since I don't have enough experience in ...
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847 views

Avoiding microstrip line to become CPWG

I have been designing RF PCBs for a year for an RF front-end system. One of my PCBs has very strict constraints about its size measurements. So, I should design it very densely. The problem with ...
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48 views

Request for a RF technolgy [closed]

Request you to suggest a RF module which can communicate over a distance of 3km as shown in the below figure Application: used in farming field
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28 views

Stream Audio and WebCam Video through Radio Frequency

I and my friend would love to make a better communication system between us since his internet connection is not the best and neither is mine. We are 20 km away from each other. Our project is to ...
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28 views

Transmitting VLF RF signal using a LW transmitter [duplicate]

In reference to a previous thread I have created a visual basic 6 program that can output an audio sine wave out of the 3.5 aux speaker jack on the PC soundcard. The sine wave is broadcasted as either ...
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Is HID 125 kHz mini mullion proximity reader Compatible with Suprema DM-20 and Corestation?

Can we use HID Proximity cards and HID 125 kHz mini mullion proximity reader for suprema DM-20 and Corestation Controller using wiegand connection? If they are compatible how many DM-20s would be ...
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53 views

Can someone please explain this Bluetooth Antenna Test Result, I am new to RF?

This is the test of a Bluetooth (BLE 5.0) passive antenna test result. I am new to RF and do not know how to properly interpret this result.
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52 views

Video transmission wirelessly [closed]

I need to transmit a video file wirelessly. Its size will be 3Mb maximum. Resolution depends on the video and i can change the fps value as i wish. The video file will be given in a SD card or a ...
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30 views

BLE beacons advertising frequencies collision

I'm designing a smartphone app that gets advertising transmissions from N BLE beacons that transmit to M meters (approximately), for kind-of indoor-navigation. My goal is to maximize N and M as ...
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36 views

TCXO with tune-able Frequency

Hello I need a TCXO with tunable frequency 10 to 12MHz. I find the part here A18ST but this company is not responding and I don't find their distributors. Please help me if anyone knows a company that ...
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55 views

What causes 100Hz spuriour emissions on AD9850 WSPR transmitter?

I've built WSPR transmitter based on AD9850. AD9850 is driven by 125 MHz crystal. TX frequency is 14 Mhz. On the receive side there is upconverter (+125 MHZ crystal) and SDR (both RTL-SDR and AirSpy). ...
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76 views

How to drive an AD9850 at 100 kHz/s sweep using arduino or rasberry pi?

The basic problem I am interested in doing is using an ADXXX chip to make a linear frequency sweep through the HF bands, from 1-20 MHz. The sweep rate I would like to achieve is 100 kHz/s, which ...
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29 views

Si4362 Reciever operating outside band

Fellow engineers, I have RF related problem I've found interesting receiver chip which I intend to use outside designated band. Si4362 It is stated in datasheet that: Frequency range = 142–1050 ...
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20 views

Radio frequency coil for homogeneous B field over area

Are there any possibilities of creating a coil which would function at high frequency (MHz range , maybe up to a few GHz) and which would give me a B field that could be used to penetrate a certain ...
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1answer
46 views

Is there a RF signal device for a 120 or 240 vac wire to start and stop a standby generator?

Our standby generators automatically start when a switch in the automatic transfer switch closes and the gen stops when that switch opens. Usually we bury 2 16ga wires along with two 120/240v hot and ...
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Whats the difference in these 2 input filter dampers?

Hi Im designing input filter for tps54202, with input 12V, output 3.3V at 0.5A. To pass emission test I need input filter, L+C should be good for that, but Ive read that its good to add damper to get ...
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31 views

RF shield needed for BLE SoC in PCB design

I´m checking the implications of using BLE in a new design. This design will include in the same PCB a BLE SoC, the specific matching network and an anetnna (still checking if I´m going to use a ...
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133 views

How to deal with ground in VCCed-chassis device?

I'm restoring old USSR radio receiver ("Okean-209"). I've already resoldered all electrolytic capacitors so audio amplifier works great again (there was very low sound before that). However, there are ...
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59 views

Extending an RF ground plane outside a small PCB

I am making an RF PCB with a surface-mount antenna on it. It is a quarter-wave antenna, so the ground plane should also be as long as a quarter wavelength for good RF performance. For example, a ...
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52 views

Measurement of s11 with reduced power on NanoVNA

I am developing a 10.7 MHz IF amplifier for a radio receiver. In order to match the input to the output of the driving mixer stage (330 ohm) I need to measure the input impedance. I did the ...
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33 views

Task of the Driver on Mach Zehnder Modulator

What is the task of the Driver of the MZM modulator? I'm trying to get RF input for the MZM, does the driver convert optical input to RF? We have a driver, what's the purpose of it? How can I design ...
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43 views

Doubts about a differential negative resistance oscillator

let's consider this kind of differential negative resistance oscillator: The output of this circuit is VA - VB. My book says the following sentence: From a quick analysis of the circuit it can be ...
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29 views

How can I setting up RF2506?

I'm going to use RF2506 IC in my project. But I want to know How can I calculate the output frequency. I searched the Internet but I find nothing. I want to change only VTUNE voltage to control the ...
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67 views

How to add a 4g / 5g feature on a single board computer design with a cheap price?

Let's assume, I am planning do design my own single board computer just as a hobby regardless of whether it is wise or not. Searching online has made me so confused. In general, I see two options: ...
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39 views

Impedance matching an amplifier near 1 dB compression point

I am using a RF amplifier (model: Minicircuits LZY-22+) to drive 6.5 MHz oscillation in a coil. I am using an antenna tuner (model: MFJ-969) to impedance-match the output of the amplifier to the coil. ...
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69 views

In Amplitude Modulation transmission, why do we need to mix (multiply) rather than just add the carrier and base-band?

Why is it necessary to mix the carrier with the message signal to create the sum and difference of the frequencies when you can just add both signal? Not only is it much easier to achieve but it would ...
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47 views

How this remote control generates radio signal?

I have this RF remote control that I'm trying to understand (here is spec: http://www.telran.co.il/images/980305%20QK-M04%20TECH%20SPECS.pdf ). I recognize crystal oscillator that is responsible for ...
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43 views

4G LTE: Is it possible to make a high gain antenna that resonates well for two frequencies, where one isn't a close harmonic of the other?

I want a high gain antenna for Verizon LTE data to my JetPack 7730L but don't really see one as high as say this MIMO parabolic antenna that's probably design for 2.4 GHz WiFi. From all I know it's ...
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38 views

Zero - IF receiver main limits

I was reading these slides about receivers architectures, and I have some questions about Zero - IF receivers: Precisely: Why is the spectrum around the carrier (i.e. the 2 "side bands") mirrored ...
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36 views

Building a Bluetooth dongle from scratch

I am trying to build a custom wireless mouse and I was initially a bit confused on how "wireless" can be implemented. What I was confused about is how some mice have dongles while others simply pair ...
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48 views

RF signal Multiplier or Chopper

I'm trying to design a circuit that "multiplies" two signals. I have an electrical unit with two separate circuits. One circuit drives the other one with a square signal. The width of the square ...
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1answer
36 views

Good solution for TPS54202 input filter design?

I trying to make tps54202 switch regulator for esp32-wroom which would pass EMC test. https://www.ti.com/tool/TIDA-00948 By reading guidelines of designing they say that to pass EMC test you need to ...
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94 views

Can I use a 2.4 GHz rated parabolic MIMO antenna for 700 MHz Verizon 4G LTE data?

Can I use a 2.4 GHz rated parabolic MIMO antenna for 700 MHz Verizon 4G LTE data? It seems 700 MHz are a long ways from the range of a 2.4 GHz antenna, but I have seen people marketing similar ...
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29 views

Antenna Tuning for a Multi-band Antenna

I have PCB antenna . which support multiple band antenna. https://www.johansontechnology.com/datasheets/0830AT54A2200/0830AT54A2200.pdf we also have tune circuit before antenna as recommended by ...
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26 views

Can capacitors be used to make a low-impedance ECL termination voltage?

I am trying to develop a circuit in which an RF sinusoid is put into the input of the ADCMP552 PECL output comparator and then the PECL output (square wave ish) is input to the MC100EP140 phase ...
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54 views

Is the TPS54202 buck converter a good solution to pass the FCC SDoC?

I want to design a PCB with the ESP32-WROOM module which has bluetooth. I want to pass the FCC verification. I would use a linear regulator, but it makes too much heat. My input is 14V car battery, ...
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42 views

Value of loop gain for steady state oscillations

I was reading on a book (High-Frequency Oscillator Design for Integrated Transceivers, J. van der Tang, Dieter Kasperkovitz, Arthur H.M. van Roermund) this paragraph about the start-up condition for ...
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Why are tv aerial cables so mysteriously sensitive to their positioning and the proximity of people?

Digital TV Reception is not great in our area and sometimes we lose reception when conditions aren't favourable. Being UK Freeview, I'm pretty sure it uses the DVB-T2 standard. Anyway, when ...
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60 views

How is the closed loop transfer function defined for an oscillator?

an electronic oscillator is a device which can generate some signals without input signals. It is an unstable system realized with positive feedback, as shown in the following scheme: Now I have two ...
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65 views

Relationship between radio transmitter output power and its input electrical power?

Given a radio station of a given licensed effective radiated power, is it the case that the transmitter requires at least that much mains power to run it? E.g., if a radio station says it's 100,000 ...
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75 views

Direction finder for cross country navigation while dayhiking - antenna considerations [closed]

Edit: I'm looking for an antenna, not criticism on whether I need one, all the rest is just background😉 My family enjoys short day hikes through heavily wooded countryside with mild hills.(Northen ...

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